SSL_CTX_sess_set_get_cb(3SSL) OpenSSL SSL_CTX_sess_set_get_cb(3SSL)NAME
SSL_CTX_sess_set_new_cb, SSL_CTX_sess_set_remove_cb, SSL_CTX_sess_set_get_cb,
SSL_CTX_sess_get_new_cb, SSL_CTX_sess_get_remove_cb, SSL_CTX_sess_get_get_cb - provide
callback functions for server side external session caching
SYNOPSIS
#include <openssl/ssl.h>
void SSL_CTX_sess_set_new_cb(SSL_CTX *ctx,
int (*new_session_cb)(SSL *, SSL_SESSION *));
void SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx,
void (*remove_session_cb)(SSL_CTX *ctx, SSL_SESSION *));
void SSL_CTX_sess_set_get_cb(SSL_CTX *ctx,
SSL_SESSION (*get_session_cb)(SSL *, unsigned char *, int, int *));
int (*SSL_CTX_sess_get_new_cb(SSL_CTX *ctx))(struct ssl_st *ssl, SSL_SESSION *sess);
void (*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx))(struct ssl_ctx_st *ctx, SSL_SESSION *sess);
SSL_SESSION *(*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx))(struct ssl_st *ssl, unsigned char *data, int len, int *copy);
int (*new_session_cb)(struct ssl_st *ssl, SSL_SESSION *sess);
void (*remove_session_cb)(struct ssl_ctx_st *ctx, SSL_SESSION *sess);
SSL_SESSION *(*get_session_cb)(struct ssl_st *ssl, unsigned char *data,
int len, int *copy);
DESCRIPTION
SSL_CTX_sess_set_new_cb() sets the callback function, which is automatically called
whenever a new session was negotiated.
SSL_CTX_sess_set_remove_cb() sets the callback function, which is automatically called
whenever a session is removed by the SSL engine, because it is considered faulty or the
session has become obsolete because of exceeding the timeout value.
SSL_CTX_sess_set_get_cb() sets the callback function which is called, whenever a SSL/TLS
client proposed to resume a session but the session could not be found in the internal
session cache (see SSL_CTX_set_session_cache_mode(3)). (SSL/TLS server only.)
SSL_CTX_sess_get_new_cb(), SSL_CTX_sess_get_remove_cb(), and SSL_CTX_sess_get_get_cb()
allow to retrieve the function pointers of the provided callback functions. If a callback
function has not been set, the NULL pointer is returned.
NOTES
In order to allow external session caching, synchronization with the internal session
cache is realized via callback functions. Inside these callback functions, session can be
saved to disk or put into a database using the d2i_SSL_SESSION(3) interface.
The new_session_cb() is called, whenever a new session has been negotiated and session
caching is enabled (see SSL_CTX_set_session_cache_mode(3)). The new_session_cb() is
passed the ssl connection and the ssl session sess. If the callback returns 0, the session
will be immediately removed again.
The remove_session_cb() is called, whenever the SSL engine removes a session from the
internal cache. This happens when the session is removed because it is expired or when a
connection was not shutdown cleanly. It also happens for all sessions in the internal
session cache when SSL_CTX_free(3) is called. The remove_session_cb() is passed the ctx
and the ssl session sess. It does not provide any feedback.
The get_session_cb() is only called on SSL/TLS servers with the session id proposed by the
client. The get_session_cb() is always called, also when session caching was disabled. The
get_session_cb() is passed the ssl connection, the session id of length length at the
memory location data. With the parameter copy the callback can require the SSL engine to
increment the reference count of the SSL_SESSION object, Normally the reference count is
not incremented and therefore the session must not be explicitly freed with
SSL_SESSION_free(3).
SEE ALSOssl(3), d2i_SSL_SESSION(3), SSL_CTX_set_session_cache_mode(3), SSL_CTX_flush_sessions(3),
SSL_SESSION_free(3), SSL_CTX_free(3)1.0.0e 2003-03-27 SSL_CTX_sess_set_get_cb(3SSL)